Oligothiophene phosphoramidites for oligonucleotide labelling

We report the synthesis and characterization of two oligonucleotides (a tetramer and a 19-mer) labelled with a fluorescent oligothiophene and obtained by means of the phosphoramidite of the fluorophore. The conjugate compounds were synthesized in solid phase and characterized by means of mass spectrometry, multinuclear NMR, UV-vis and photoluminescence spectroscopies. The results show that this approach is suitable as a general route for the preparation of oligonucleotides labelled with oligothiophene-based fluorophores.